In this issue of ABO (Arquivos Brasileiros de Oftalmologia) we formally acknowledge and express our gratitude to the voluntary hard and substantial work, commitment and proficiency of our peer reviewers. We could not thank them enough for their immense cooperation to our journal and, why not, visual sciences. That said, we could state that the essential impartiality and quality of scientific publishing is provided by peer reviewers^{( 1 - 7 )}.

Peer review is defined as the "critical assessment of manuscripts submitted to journals by experts who are not part of the editorial staff" by the International Committee of Medical Journal Editors. Journal’s editors may not have accurate expertise to provide complete and impartial reviews of all themes considered for publication. Reviewers are chosen based on their knowledge about a subject or subspecialty. Peer review aims to improve science writing and editing, and medical publications deeply rely on its quality. They help editors to decide whether to publish a manuscript and provide critical feedback aiming to raise the quality of the manuscript’s final version. Considering that a reviewer delay can potentially affect the career of younger colleagues, who are relying on a publication for promotion or tenure, reviewers work carries a "great power" and is associated to a huge responsibility^{( 8 , 9 )}.

Properly conducted peer review offers a great chance to learn from others experience and improve quality and safety of health care with the best available scientific discoveries and proper analysis. Reviewers check for inconsistencies, biases, wrong methodology and frauds. Incorrect reviews may lead to erroneous editorial decisions and good science might be rejected for bad reasons (even manuscripts that later resulted in a Nobel Prize have been rejected for publication)^{( 9 )}. On the other hand, imprecise, misleading and partial data can be printed and negatively impact our patients. Clinical decisions are affected based in published results, having a direct impact on patient care^{( 10 , 11 )}.

There are no "formal training" programs for peer reviewers. Hence, although universally used, peer review is time-consuming, imperfect, largely subjective, present low reproducibility even under optimal research conditions and may fail to notice important deficiencies. Why does it happen? First of all, we have to state that medicine is very complex, and few (if any) outcome have a single sufficient and necessary cause. Besides that, many methodological biases (e.g.: sample selection, data extraction and analysis, statistical analysis, etc…) may affect decision making and lead to error. Also the competitiveness in research ("publish or perish") and limited grant funding opportunities may induce one to publish results from a single study into multiple (redundant) publications, plagiarize, fabricate or fraud scientific information^{( 1 , 2 , 5 , 7 )}.

Reviewers are more likely to accept to evaluate a manuscript when the paper represents an opportunity to learn something new, its data is relevant and contribute to their area of expertise. A sense of professional duty, part of academic role and the reputation of the journal are also key factors. The most motivating incentives included free access to the journal, annual acknowledgement of reviewers published on the journal, feedback about the outcome of the manuscript submission and the quality of their reviews, and the appointment of the best reviewers to the journal’s editorial board. Lack of time is the major factor in the decision to decline. Others reasons include conflict of interests and a tight deadline to complete the review^{( 3 )}.

Receiving adequate peer review for manuscripts is really a great challenge, can affect quality and result in publication delay. Most skilled reviewers are those with a respectable track record of own publications in high-quality periodicals, expertise in epidemiology or statistics, current involvement in research, affiliation to a University hospital and several reviewer contributions^{( 8 )}. It is not easy to find! The exponential growth of manuscripts submitted for publication overburdens the capability of available qualified referees and challenges the maintenance of quality on their evaluations and respect timelines^{( 7 )}.

We have the privilege of counting with the contribution of world renowned specialists, who makes valuable revisions. We strongly support this formal recognition of their contribution and respectfully express our thankfulness for sharing your valuable time with ABO and its readers.